This invention relates generally to fasteners, and more particularly, to plastic fasteners for holding members together without the use of screws or bolts.
From time to time it is desirable to connect or fasten two pieces of material or two objects to each other in a simple and efficient manner. Historically, members were joined using nails, screws, bolts, welding and other joining and connecting methods. While these methods certainly accomplish the task of joining the members, by and large, they were inefficient, time consuming, and required the use of tools. From time to time, it was also desirable to bundle materials using twine or wire or some other material to secure the bundle. While string is effective in securing materials in a bundle, it is time consuming and the string is subject to wear and eventual breakage. Accordingly, it will be appreciated that it would be highly desirable to provide a simple, efficient fastener which does not require tools to assemble and which is wear resistant.
As in other fields of technology, modern plastic materials are being used in fasteners. One such fastener is described in U.S. Pat. No. 3,748,696 which issued July 31, 1973 to M. F. Martin. Martin discloses a plastic fastener for joining objects together wherein a bolt member has a sharpened shank which pierces the object to be joined. The bolt member also has normally outwardly projecting but inwardly flexible anchor members formed integrally on the shank to engage shoulders on a nut member. After the bolt pierces the object, the nut is forced axially onto the bolt shank, flexing the anchor members inwardly. The anchor members then spring out into engagement with internal shoulders in the bore of the nut to hold the nut onto the bolt. The shank is sharpened so that it may be driven into the objects to be joined with aid of the hammer of similar tool. The shank and nut of the fastener can be connected with a connecting strip so that the fastener may be used to secure bundles. Martin designed this fastener for use in securing tire carcasses together to form structural objects for use in fresh and salt water environments. In such an application, it is not necessary that there be no relative motion between the two members which are secured together by the fastener. However, when assembling electrical equipment such as a load center or when assembling machine parts or other things that require close tolerances, relative motion between the parts to be joined must be limited. Accordingly, it would be appreciated that it would be highly desirable to provide a simple plastic fastener which secures the parts together and minimizes the relative motion between parts.
When using plastic materials such as nylon, for example, the parts of the fastener are force fitted together so that one of the plastic members is deformed during assembly and is required to reform after assembly so that the parts are securely held together. While this is possible, it is extremely difficult to achieve and almost impossible while the fastener may be subject to forces tending to separate the parts so joined. Accordingly, it will be appreciated that it would be highly desirable to have a fastener in which the parts are force fitted together forming a connection and which is assisted in the reforming process so that the completed fastener assembly withstands separation forces and provides a dimensionally precise connection.
It is an object of the present invention to provide a plastic fastener.
Another object of the present invention is to provide a plastic fastener which can be used in applications requiring dimensional tolerances.
Still another object of the present invention is to provide a fastener which is adaptable to assembly using an assembly machine.